GENETIC VARATION FOR YIELD AND QUALITY TRAITS OF DURUM WHEAT (Triticum durum L.) GENOTYPE UNDER WATER- LOGGING CONDITION IN CENTRAL HIGHLANDS OF ETHIOPIA

This study was conducted to assess the genetic variation of 100 durum wheat genotypes under water logging condition, determine associations among agro morphology and quality traits of durum wheat, and also to assess the degree of genetic diversity among the genotypes. The experiment was laid out in 10 x 10 simple lattice design during 2017cropping season at Debre Zeit and Chefe Donsa research sites. The analysis of variance showed that mean squares due to genotype and location by genotype interaction were highly significant (P≤0.01) for all 21 studied traits of combined analysis. While, location effects were highly significant (P≤0.01) for all traits except for biological yield, harvest index, grain yield and number of kernels per spike. As a result, the genotypes had significant variations for grain yield with the range between 3515.25 kg/ha to 7539.25 kg/ha with over all mean value of 5788.98kg/ha. The maximum grain starch percentage of the genotypes was 68.13% (CD15DZ-ELT/1094/2015), while the minimum was 64.53% for (CD15DZ-ELT/off/1144/2015). The total grain protein content varied from 11.43% for (CD15DZ-ELT/off/1035/2015 to 15.38% for genotype (CD15DZ_ELT/off/943/2015). The traits which had high PCV and GCV were grain yield, thousand grain weight, number of kernels per spike, harvest index, and sedimentation volume. The estimated values of H2B and GAM ranged from 61.82% to 92.48%, and 3.92% to 78.35%, respectively; the maximum and the minimum values being associated with grain starch percentage, plant height and gluten index, respectively in both cases. Considering the association of characters, grain yield (kg/h) showed highly significant and positive correlation with biomass yield, harvest index, number of effective tillers, and number of kernels per spike at both phenotypic and genotypic levels, while highest positive genotypic and phenotypic direct effect on grain yield was exhibited by harvest index and biological yield. Days to heading exerted high negative (-0.74) and positive (0.79) direct effects on grain yield at genotypic and phenotypic levels, respectively. In this study, seven significant Principal Components which explained cumulatively 83.7% of the total variation were extracted. The genetic distance for all possible pairs of the genotypes ranged from 46.73 to 10723.31. Accordingly, the 100 durum wheat genotypes were grouped into four distinct clusters. However, among four main clusters in the Dendrogram, clusters I and II accounted for the maximum cluster means and contained the most divergent genotypes. Comparatively, depending on the present result, clusters II and IV were characterized by high yielder genotypes possessing better yield related traits as well as potential sources for quality traits improvement as compared to genotypes in the remaining clusters. Generally, the present study revealed high genetic variation among the tested durum wheat genotypes and hence, can serve as source of germplasm for durum wheat improvement under high water-logging conditions in the central highlands of Ethiopia where durum wheat is dominantly growing.